The structure of the fuselage of an aircraft generally includes criss-crossing circumferential frames of globally circular shape lying in planes transverse to the axial direction of the aircraft and longitudinal stringers. A structure of this kind makes it possible to impart a stable geometry to the fuselage skin.
A notable function of the circumferential frames is to resist the loads induced by the pressurization of the cockpit and the cabin of the aircraft. To this end, the frames typically have a T-shape, I-shape, L-shape or other shape section and therefore comprise a web and a flange substantially orthogonal to the web. The fuselage skin is fixed to this flange, also referred to as the “chord member”.
In the greater part of the fuselage of aircraft of known type, the skin is of circular cylindrical general shape with the result that the web of each circumferential frame is substantially orthogonal to the skin. This configuration is the optimum in terms of resistance to the loads induced by pressurization.
On the other hand, in the nose section and in the tail section of the aircraft, the fuselage skin has a double curvature with the result that the respective webs of the circumferential frames in these regions of the aircraft are not orthogonal to the fuselage skin.
Because of this, this type of fuselage structure is not the optimum in terms of resistance to pressurization forces.